| Cadmium (Cd) | A chemical element used in making certain types of solar cells and batteries. |
| Cadmium Telluride (Cdte) | A polycrystalline thin-film photovoltaic material. |
| Caldera | a bowl-shaped landform, created either by a huge volcanic explosion (which destroys the top of a volcano) or by the collapse of a volcano’s top. |
| Call-Back | A provision included in some power sale contracts that lets the supplier stop delivery when the power is needed to meet certain other obligations. |
| Calorie | One energy calorie is equivalent to 4.2 joules. Thus, it takes 500,000 calories of energy to boil a pot of coffee. One food calorie equals 1,000 energy calories. |
| Calorie (Energy Calorie | small "c" |
| Capacitance | An electrical effect in AC circuits that results in amperage peaking before voltage. |
| Capacitor | An electronic component used for the temporary storage of electricity, as well for removing unwanted noise in circuits. A capacitor will block Direct Current but will pass Alternating Current. |
| Capacity | See Battery Capacity. |
| Capacity (C) | See battery capacity. |
| Capacity Factor | The ratio of the average load on (or power output of) an electricity generating unit or system to the capacity rating of the unit or system over a specified period of time. |
| Capacity Release | A secondary market for capacity that is contracted by a customer which is not using all of its capacity. |
| Captive Customer | A customer who does not have realistic alternatives to buying power from the local utility, even if that customer had the legal right to buy from competitors. |
| Captive Electrolyte Battery | A battery having an immobilized electrolyte (gelled or absorbed in a material). |
| Carbon Dioxide | A colorless, odorless, non-poisonous gas that is a normal part of the air. Carbon dioxide, also called CO2, is exhaled by humans and animals and is absorbed by green growing things and by the sea. |
| Carbon Dioxide (Co2) | A colorless, odorless noncombustible gas present in the atmosphere. It is formed by the combustion of carbon and carbon compounds (such as fossil fuels and biomass), by respiration, which is a slow combustion in animals and plants, and by the gradual oxidation of organic matter in the soil. |
| Carbon Monoxide (Co) | A colorless, odorless but poisonous combustible gas. Carbon monoxide is produced in the incomplete combustion of carbon and carbon compounds, for example, fossil fuels like coal and petroleum. |
| Carcinogens | Potential cancer-causing agents in the environment. They include among others: industrial chemical compounds found in food additives, pesticides and fertilizers, drugs, toy, household cleaners, toiletries and paints. Naturally occurring ultraviolet solar radiation is also a carcinogen. |
| Catalytic Cracking | A refinery process that converts a high-boiling range fraction of petroleum (gas oil) to gasoline, olefin feed for alkylation, distillate, fuel oil and fuel gas by use of a catalyst and heat. |
| Cathode | The negative pole or electrode of an electrolytic cell, vacuum tube, etc., where electrons enter (current leaves) the system; the opposite of an anode. |
| Cathodic Protection | A method of preventing oxidation (rusting) of exposed metal structures, such as bridges and pipelines, by imposing between the structure and the ground a small electrical voltage that opposes the flow of electrons and that is greater than the voltage present during oxidation. |
| Caulking | Material used to make an air-tight seal by filling in cracks, such as those around windows and doors. |
| Cd | see cadmium. |
| CdTe | see cadmium telluride. |
| Cell | The basic unit of a PV module or battery. The most basic unit that contains the necessary materials, such as electrodes and electrolyte in a battery, to produce electricity. |
| CELL (Battery) | A single unit of an electro-chemical device capable of producing an electrical current by converting chemical energy into electrical energy. The cell is the basic unit used to store energy in the battery. The cell contains an anode, a cathode, and the electrolyte. A battery usually consists of several cells electrically connected together to produce higher voltages. (Sometimes the terms cell and battery are used interchangeably). |
| CELL (Solar) | The smallest, basic photovoltaic device that generates electricity when exposed to light. |
| Cell Barrier | A very thin region of static electric charge along the interface of the positive and negative layers in a photovoltaic cell. The barrier inhibits the movement of electrons from one layer to the other, so that higher-energy electrons from one side diffuse preferentially through it in one direction, creating a current and thus a voltage across the cell. Also called depletion zone or space charge. |
| Cell Efficiency | The ratio of the electrical energy produced by a photovoltaic cell (under full sun conditions or 1 kw/m2) to the energy from sunlight falling upon the photovoltaic cell. |
| Cell Junction | The area of immediate contact between two layers (positive and negative) of a photovoltaic cell. The junction lies at the center of the cell barrier or depletion zone. |
| Celsius | A temperature scale based on the freezing (0 degrees) and boiling (100 degrees) points of water. Abbreviated as C in second and subsequent references in text. Formerly known as Centigrade. To convert Celsius to Fahrenheit, multiply the number by 9, divide by 5, and add 32. For example: 10 degrees Celsius x 9 = 90; 90 / 5 = 18; 18 + 32 = 50 degrees Fahrenheit. |
| Central Power Plant | A large power plant that generates power for distribution to multiple customers. |
| CFCS (Chlorofluorocarbons Or Chlorinated Fluorocarbons) |
A family of artificially produced chemicals receiving much attention for their role in stratospheric ozone depletion. On a per molecule basis, these chemicals are several thousand times more effective as greenhouse gases than carbon dioxide. Since they were introduced in the mid-1930s, CFCs have been used as refrigerants, solvents and in the production of foam material. The 1987 Montreal protocol on CFCs seeks to reduce their production by one-half by the year 1998. |
| CFM (Cubic Feet Per Minute) | A measure of flow rate. CURIE |
| Charge | Electricity produced by a surplus (position) or shortage (negative) of electrons in an object. |
| Charge Carrier | A free and mobile conduction electron or hole in a semiconductor. |
| Charge Controller | A component of a photovoltaic system that controls the flow of current to and from the battery to protect it from over-charge and over-discharge. The charge controller may also indicate the system operational status. |
| Charge Factor | A number corresponding to the time (in hours) for which a battery can be charged at a constant current without damaging it. Usually expressed as a function of battery capacity, e.g. C/10 indicates a charge factor of 10 hours. Related to Charge Rate. |
| Charge Rate | A measure of the current used to charge a battery as a proportion of its capacity. |
| Chemical Energy | The energy liberated in a chemical reaction, as in the combustion of fuels. |
| Chemical Vapor Deposition (Cvd) | A method of depositing thin semiconductor films used to make certain types of photovoltaic devices. With this method, a substrate is exposed to one or more vaporized compounds, one or more of which contain desirable constituents. A chemical reaction is initiated, at or near the substrate surface, to produce the desired material that will condense on the substrate. |
| Chiller | A device that cools water, usually to between 40 and 50 degrees Fahrenheit for eventual use in cooling air. |
| Chinook | A warm, dry wind that originates with moist wind from the Pacific Ocean and releases its moisture as precipitation over the Rocky Mountains. The air is then compressed and heated as it descends over the frozen plains of the northwestern United States and Canada, often melting several inches of snow in a matter of hours. This leads some people to call these winds snow eaters. |
| Circuit | A group of electrical components that make a complete electrical path, providing some function. |
| Circuit Breaker | A device used to interrupt or break an electrical circuit when an overload condition exists. Circuit breakers are used to protect electrical equipment from potential damage. |
| Clean Fuel Vehicle | is frequently incorrectly used interchangeably with "alternative fuel vehicle." Generally, refers to vehicles that use low-emission, clean-burning fuels. Public Resources Code Section 25326 defines clean fuels, for purposes of the section only, as fuels designated by ARB for use in LEVs, ULEVs or ZEVs and include, but are not limited to, electricity, ethanol, hydrogen, liquefied petroleum gas, methanol, natural gas, and reformulated gasoline. |
| Cleavage Of Lateral Epitaxial Films For Transfer (CLEFT) |
A process for making inexpensive Gallium Arsenide (gaas) photovoltaic cells in which a thin film of gaas is grown atop a thick, single-crystal gaas (or other suitable material) substrate and then is cleaved from the substrate and incorporated into a cell, allowing the substrate to be reused to grow more thin-film gaas. |
| Clerestory | A wall with windows that is between two different (roof) levels. The windows are used to provide natural light into a building. |
| Climate | The prevailing or average weather conditions of a geographic region. |
| Climate Zone | A geographical area is the state that has particular weather patterns. These zones are used to determine the type of building standards that are required by law. |
| Closed Loop System | A solar hot water system of which no part is vented to the atmosphere or fed with fresh liquid. The system liquid, usually some form of antifreeze solution, is recirculated. Closed loop solar systems are also known as glycol systems and indirect systems. |
| Cloud Enhancement | The increase in solar intensity caused by reflected irradiance from nearby clouds. |
| Clunkers | also known as gross-polluting or super- emitting vehicles, i.e., vehicles that emit far in excess of the emission standards by which the vehicle was certified when it was new. |
| Coal | Black or brown rock, formed under pressure from organic fossils in prehistoric times, that is mined and burned to produce heat energy. |
| Coal Conversion | Changing coal into synthetic gas or liquid fuels. See GASIFICATION. |
| Coal Oil | Oil that can be obtained by distilling bituminous coal. |
| Coal Seam | A mass of coal, occurring naturally at a particular location, that can be commercially mined. |
| Coal Slurry Pipeline | A pipe system that transports pulverized coal suspended in water. |
| Cob Construction | A traditional building technique using hand formed lumps of earth mixed with sand and straw. |
| Cogeneration | The joint production of electricity and useful heat at a single facility, resulting in more efficient use of the thermal energy. |
| Cogenerator | Cogenerators use the waste heat created by one process, for example during manufacturing, to produce steam which is used, in turn, to spin a turbine and generate electricity. Cogenerators may also be QFs. |
| Coke | A porous solid left over after the incomplete burning of coal or of crude oil. |
| Coke Oven Gas | Gas given off by coke ovens. Coke oven gas is interchangeable with goal gas. |
| Collector Loop | The plumbing loop in a solar hot water system that includes the solar collectors. The collectors heat the fluid in the collector, and the heated fluid can be used directly (if water) or the heat can be exchanged to a potable water loop. |
| Combined Collector | A photovoltaic device or module that provides useful heat energy in addition to electricity. |
| Combined Cycle Plant | An electric generating station that uses waste heat from its gas turbines to produce steam for conventional steam turbines. |
| Combined Hydronic Space/Water Heating | a system in which both space heating and domestic water heating are provided by the same water heater(s). |
| Combiner Box | A box where wires from individual PV modules or strings are combined into larger wires to run to the battery bank. Can also contain overcurrent protection devices. |
| Combustion | the burning of gas, liquid, or solid, in which the fuel is oxidized, producing heat and often light. |
| Combustion Burning | Rapid oxidation, with the release of energy in the form of heat and light. |
| Comfort Conditioning | The process of treating air to simultaneously control its temperature, humidity, cleanliness, and distribution to meet the comfort requirements of the occupants of the conditioned space. |
| Comfort Zone | The range of temperatures over which the majority of persons feel comfortable (neither too hot nor too cold). |
| Commercialization | Programs or activities that increase the value or decrease the cost of integrating new products or services into the electricity sector. (See "Sustained Orderly Development.") |
| Compact Fluorescent Light (Cfl) | A smaller version of standard fluorescent lamps that can directly replace incandescent lights. Cfls use 65 to 80 percent less energy, while producing the same lumens. |
| Competitive Transmission Charge | A non-bypassable charge that customers pay to a utility for the recovery of its stranded costs. |
| Compressed Natural Gas (Cng) | natural gas that has been compressed under high pressure, typically between 2,000 and 3,600 pounds per square inch, held in a container. The gas expands when released for use as a fuel. |
| Concentrating Solar Power (CSP) systems | concentrate the sun�s energy using reflective devices, such as troughs or mirror panels, to produce heat that is used for industrial processes or to generate electricity. |
| Concentrator | A photovoltaic module, which includes optical components such as lenses (Fresnel lens) to direct and concentrate sunlight onto a solar cell of smaller area. Most concentrator arrays must directly face or track the sun. They can increase the power flux of sunlight hundreds of times. |
| Condensate | Liquid fuel obtained by burning gas or vapor produced from oil and gas wells. |
| Condense | to change from a gas to drops of liquid. Water-cooled geothermal power plants use cooling towers to cool the used steam and condense it back to water for injection back to the edge of the reservoir. In binary power plants, an organic liquid is first vaporized (with heat from geothermal water) to drive a turbine, then cooled and condensed back to a liquid and recycled again and again in a closed loop. |
| Condenser | A heat exchanger in which the refrigerant, compressed to a hot gas, is condensed to liquid by rejecting heat. |
| Conditioned Space, Directly | An enclosed space that is provided with heating equipment that has a capacity exceeding 10 Btus/(hr-ft2), or with cooling equipment that has a capacity exceeding 10 Btus/(hr-ft2). An exception is if the heating and cooling equipment is designed and thermostatically controlled to maintain a process environment temperature less than 65 degrees Fahrenheit or greater than 85 degrees Fahrenheit for the whole space the equipment serves |
| Conductance | The quantity of heat, in Btu’s, that will flow through one square foot of material in one hour, when there is a 1 degree F temperature difference between both surfaces. Conductance values are given for a specific thickness of material, not per inch thickness. |
| Conduction | Heat transfer from a hot object to a colder object through direct contact. |
| Conduction Band (Or Conduction Level) | An energy band in a semiconductor in which electrons can move freely in a solid, producing a net transport of charge. |
| Conductivity (K) | The quantity of heat that will flow through one square foot of homogeneous material, one inch thick, in one hour, when there is a temperature difference of one degree Fahrenheit between its surfaces. |
| Conductor | A material with relatively low resistance through which electricity will readily flow�wires, cables, busbars. The most common conductors are copper and aluminum. |
| Conduit | A pipe or elongated box used to house and protect electrical cables. |
| Congestion | A condition that occurs when insufficient transfer capacity is available to implement all of the preferred schedules simultaneously. |
| Congestion Management | Alleviation of congestion by the ISO. |
| Conservation | Steps taken to cause less energy to be used than would otherwise be the case. These steps may involve improved efficiency, avoidance of waste, reduced consumption, etc. They may involve installing equipment (such as a computer to ensure efficient energy use), modifying equipment (such as making a boiler more efficient), adding insulation, changing behavior patterns, etc. |
| Constant-Speed Wind Turbines | Wind turbines that operate at a constant RPM (rotor revolutions per minute). They are designed for optimal energy capture at a specific rotor diameter and at a particular wind speed. |
| Contact Resistance | The resistance between metallic contacts and the semiconductor. |
| Continental Drift | the theory that the continents have drifted apart when a supercontinent, Pangaea, broke apart. See Plate Tectonics. |
| Continental Shelf | The portion of the sea bottom that slopes gradually from the edge of a continent. Usually defined as areas where water is less than 200 meters or 600 feet deep. |
| Contingency Planning | The Energy Commission’s strategy to respond to impending energy emergencies such as curtailment or shortage of fuel or power because of natural disasters or the result of human or political causes, or a clear threat to public health, safety or welfare. |
| Continuous Output Rating | The maximum amount of power an inverter may deliver to a load (or loads) for a sustained period of time. |
| Contract Path | The most direct physical transmission tie between two interconnected entities. When utility systems interchange power, the transfer is presumed to take place across the "contract path," notwithstanding the electrical fact that power flow in the network will distribute in accordance with network flow conditions. This term can also mean to arrange for power transfer between systems. (See also Parallel path flow) |
| Contracts For Differences (Cfd) | A type of bilateral contract where the electric generation seller is paid a fixed amount over time which is a combination of the short-term market price and an adjustment with the purchaser for the difference. For example, a generator may sell a distribution company power for ten years at 6-cents/kilowatt-hour (kWh). That power is bid into Poolco at some low /kWh value (to ensure it is always taken). The seller then gets the market clearing price from the pool and the purchaser pays the producer the difference between the Poolco selling price and 6-cents/kWh (or vice versa if the pool price should go above the contract price). |
| Control Area | An electric power system, or a combination of electric power systems, to which a common automatic generation control (AGC) is applied to match the power output of generating units within the area to demand. |
| Convection | 1Heat transfer by the movement of fluid (usually air or water). 2 Heat transfer through either the natural or forced movement of air |
| Convection Currents | the currents caused by hot air or fluid rising and falling. Hot air or fluid expands and is therefore less dense than its cooler surroundings, thus it rises; as it cools it contracts, becomes more dense and sinks down creating something of a rolling motion. These motions are thought to be party of the dynamic geologic processes that drive the movement of crustal plates. See Plate Tectonics |
| Conventional Fuel | The fossil fuels |
| Conventional Gas | Natural gas occurring in nature, as opposed to synthetic gas. |
| Conversion | device or kit by which a conventional fuel vehicle is changed to an alternative fuel vehicle. |
| Conversion Efficiency | The ratio of the electrical energy generated by a solar PV cell to the solar energy impacting the cell. Also see: photovoltaic (conversion) efficiency |
| Conversion Fuel Factor | A number stating units of one system in corresponding values of another system. |
| Converted Vehicle | a vehicle originally designed to operate on gasoline that has been modified or altered to run on an alternative fuel. |
| Converter | An electronic device for DC power that steps up voltage and steps down current proportionally (or vice-versa). |
| Cooling Capacity, Latent | Available refrigerating capacity of an air conditioning unit for removing latent heat from the space to be conditioned. |
| Cooling Capacity, Sensible | Available refrigerating capacity of an air conditioning unit for removing sensible heat from the space to be conditioned. |
| Cooling Capacity, Total | Available refrigerating capacity of an air conditioner for removing sensible heat and latent heat from the space to be conditioned. |
| Cooling Degree Day | A unit of measure that indicates how heavy the air conditioning needs are under certain weather conditions. |
| Cooling Load | The rate at which heat must be extracted from a space in order to maintain the desired temperature within the space. |
| Cooling Load Temperature Difference (Cltd) | A value used in cooling load calculations for the effective temperature difference (delta T) across a wall or ceiling, which accounts for the effect of radiant heat as well as the temperature difference. |
| Cooling Tower | A device for evaporatively cooling water by contact with air. |
| Co-Op | This is the commonly used term for a rural electric cooperative. Rural electric cooperatives generate and purchase wholesale power, arrange for the transmission of that power, and then distribute the power to serve the demand of rural customers. Co-ops typically become involved in ancillary services such as energy conservation, load management and other demand-side management programs in order to serve their customers at least cost. |
| Cooperative (Electric Utility) | A joint venture organized by consumers to make electric utility service available in their area. |
| Copper Indium Diselenide (Cuinse2, Or CIS) | A polycrystalline thin-film photovoltaic material (sometimes incorporating gallium (CIGS) and/or sulfur). |
| Core (Outer And Inner) | the extremely hot center of the Earth. The outer core is probably molten rock and is located about 3,200 miles (5,100) kilometers down from the earth�s surface; the inner core may be solid iron and is found a the very center of the Earth- about 4,000 miles (6,400 kilometers) down. |
| Corporate Average Fuel Economy (Cafe) | A sales-weighted average fuel mileage calculation, in terms of miles per gallon, based on city and highway fuel economy measurements performed as part of the federal emissions test procedures. CAFE requirements were instituted by the Energy Policy and Conservation Act of 1975 (89 Statute. 902) and modified by the Automobile Fuel Efficiency Act of 1980 (94 Statute. 1821). For major manufacturers, CAFE levels in 1996 are 27.5 miles per gallon for light-duty automobiles. CAFE standards also apply to some light trucks. The Alternative Motor Fuels Act of 1988 allows for an adjusted calculation of the fuel economy of vehicles that can use alternative fuels, including fuel-flexible and dual-fuel vehicles. |
| Cross-Flow Turbine | A turbine where the flow of water is at right angles to the axis of rotation of the turbine. Crystalline silicon |
| Crude Oil | Petroleum as found in the earth, before it is refined into oil products. Also called CRUDE. |
| Crude Oil Stocks | Stocks held at refineries and at pipeline terminals. Does not include stocks held on leases (storage facilities adjacent to the wells). |
| Crust | the solid outermost layer of the Earth, mostly consisting of rock, and ranging from 3 |
| Crystalline Silicon | A type of photovoltaic cell made from a slice of single-crystal silicon or polycrystalline silicon. |
| Cubic Foot | The most common unit of measurement of natural gas volume. It equals the amount of gas required to fill a volume of one cubic foot under stated conditions of temperature, pressure and water vapor. One cubic foot of natural gas has an energy content of approximately 1,000 Btus. One hundred (100) cubic feet equals one therm (100 ft3 = 1 therm). |
| Cultivate | to grow and tend (plants or crops), farm. |
| Current | Is the flow of electrons. Water flowing in a pipe is similar to electric current. You need voltage to make the current flow, just like water pressure is needed to make the water flow. It’s impossible to see an electric current, but it’s there � and is used to run everything from a light to your CD player. Also see: Ampere |
| Current At Maximum Power (Imp) | The current at which maximum power is available from a module. |
| Cutoff Voltage | Electrical equipment setting for the voltage level at which a battery is considered to be empty, and the discharge process is terminated. Most commonly found in inverters and charge controllers that include a feature for low voltage disconnection. |
| Cut-Off Voltage | The voltage levels at which the charge controller (regulator) disconnects the PV array from the battery, or the load from the battery. |
| Cycle | In alternating current electricity, the current flows in one direction from zero to a maximum voltage, then goes back down to zero, then to a maximum voltage in the opposite direction. This comprises one cycle. The number of complete cycles per second determines the current frequency. In the United States the standard for alternating current is 60 cycles. |
| Cycle Life | Number of charge-discharge cycles a battery can perform under specified conditions before it fails to meet its specified performance (e.g. Capacity decreases to 80% of nominal capacity). |
| Cyclone | Air spinning inward toward centers of low air pressure. Cyclones spin counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere. |
| Czochralski Process | A method of growing large size, high quality semiconductor crystal by slowly lifting a seed crystal from a molten bath of the material under careful cooling conditions. |
